okay. i need an equation for these two word problems [ x and y format, please!]

To make things look nice, Serena lit a long dinner candle when setting the table at noon for a family meal. At 3:00 PM, the candle's height had decreased to 8 inches and by 5:00 PM, the candle was only 5 1/3 inches tall. What is the relationship between the height of the candle in inches and the hours it has been burning?

While getting ready to take a bath, Brian ran some hot water in the tub, but it was much too warm. So, he turned off the hot water and started running only cold water. One minute later, there was 18.5 gallons of water in the tub, and 27.5 after 5 minutes. What is the relationship between the number of gallons of water in the bath tub and the number of minutes the cold water had been running?